On-chip transmission lines are used to connect independent active and passive components in monolithic integrated circuits (ICs). Transmission lines are designed to carry alternating current of radio frequency (RF) that is high enough so that their wave nature must be taken into account. According to the desired working frequency, on-chip transmission lines can be classified into several types that carry different electromagnetic wave modes. Among them, transverse electromagnetic wave mode (TEM) or quasi-TEM mode transmission lines are the most commonly used for on-chip applications as they have an ultra wide frequency band from DC to the cut-off frequency of their first high order mode. However, when the working frequency of integrated circuits goes into the terahertz band (0.1 THz-10 THz), existing transmission lines both on-chip and off-chip are unable to keep up with the speed. Current on-chip transmission lines have planar structures that may be conveniently fabricated and integrated using standard two-dimensional integrated circuit processing; however, these devices tend to have large ohmic, radiation and dielectric losses, particularly in the terahertz band.